Method and apparatus for providing data processing and control in medical communication system

ABSTRACT

Methods and apparatus for providing data processing and control for use in a medical communication system are provided.

RELATED APPLICATIONS

The present application claims priority under §35 U.S.C. 119(e) to U.S.Provisional Application No. 60/911,871 filed Apr. 14, 2007, entitled“Method and Apparatus for Providing Data Processing and Control inMedical Communication System”, and assigned to the Assignee of thepresent application, Abbott Diabetes Care Inc. of Alameda, Calif., thedisclosure of which is incorporated herein by reference for allpurposes.

BACKGROUND

Analyte, e.g., glucose monitoring systems including continuous anddiscrete monitoring systems generally include a small, lightweightbattery powered and microprocessor controlled system which is configuredto detect signals proportional to the corresponding measured glucoselevels using an electrometer, and RF signals to transmit the collecteddata. One aspect of certain analyte monitoring systems includes atranscutaneous or subcutaneous analyte sensor configuration which is,for example, partially mounted on the skin of a subject whose analytelevel is to be monitored. The sensor cell may use a two orthree-electrode (work, reference and counter electrodes) configurationdriven by a controlled potential (potentiostat) analog circuit connectedthrough a contact system.

The analyte sensor may be configured so that a portion thereof is placedunder the skin of the patient so as to detect the analyte levels of thepatient, and another portion or segment of the analyte sensor that is incommunication with the transmitter unit. The transmitter unit isconfigured to transmit the analyte levels detected by the sensor over awireless communication link such as an RF (radio frequency)communication link to a receiver/monitor unit. The receiver/monitor unitperforms data analysis, among others, on the received analyte levels togenerate information pertaining to the monitored analyte levels. Toprovide flexibility in analyte sensor manufacturing and/or design, amongothers, tolerance of a larger range of the analyte sensor sensitivitiesfor processing by the transmitter unit is desirable.

In view of the foregoing, it would be desirable to have a method andsystem for providing data processing and control for use in medicaltelemetry systems such as, for example, analyte monitoring systems.

SUMMARY OF THE INVENTION

In one embodiment, method and apparatus for receiving a signalassociated with an analyte level of a user, determining whether thereceived signal deviates from a predetermined signal characteristic,determining an operational state associated with an analyte monitoringdevice, comparing a prior signal associated with the analyte level ofthe user to the received signal, generating an output data associatedwith the operational state of the analyte monitoring device based on oneor more of the received signal and the prior signal, is disclosed.

These and other objects, features and advantages of the presentinvention will become more fully apparent from the following detaileddescription of the embodiments, the appended claims and the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a block diagram of a data monitoring and managementsystem for practicing one or more embodiments of the present invention;

FIG. 2 is a block diagram of the transmitter unit of the data monitoringand management system shown in FIG. 1 in accordance with one embodimentof the present invention;

FIG. 3 is a block diagram of the receiver/monitor unit of the datamonitoring and management system shown in FIG. 1 in accordance with oneembodiment of the present invention;

FIGS. 4A-4B illustrate a perspective view and a cross sectional view,respectively of an analyte sensor in accordance with one embodiment ofthe present invention;

FIG. 5 is a flowchart illustrating ambient temperature compensationroutine for determining on-skin temperature information in accordancewith one embodiment of the present invention;

FIG. 6 is a flowchart illustrating digital anti-aliasing filteringrouting in accordance with one embodiment of the present invention;

FIG. 7 is a flowchart illustrating actual or potential sensor insertionor removal detection routine in accordance with one embodiment of thepresent invention;

FIG. 8 is a flowchart illustrating receiver unit processingcorresponding to the actual or potential sensor insertion or removaldetection routine of FIG. 7 in accordance with one embodiment of thepresent invention;

FIG. 9 is a flowchart illustrating data processing corresponding to theactual or potential sensor insertion or removal detection routine inaccordance with another embodiment of the present invention;

FIG. 10 is a flowchart illustrating a concurrent passive notificationroutine in the data receiver/monitor unit of the data monitoring andmanagement system of FIG. 1 in accordance with one embodiment of thepresent invention.

DETAILED DESCRIPTION

As described in further detail below, in accordance with the variousembodiments of the present invention, there is provided a method andapparatus for providing data processing and control for use in a medicaltelemetry system. In particular, within the scope of the presentinvention, there is provided a method and system for providing datacommunication and control for use in a medical telemetry system such as,for example, a continuous glucose monitoring system.

FIG. 1 illustrates a data monitoring and management system such as, forexample, analyte (e.g., glucose) monitoring system 100 in accordancewith one embodiment of the present invention. The subject invention isfurther described primarily with respect to a glucose monitoring systemfor convenience and such description is in no way intended to limit thescope of the invention. It is to be understood that the analytemonitoring system may be configured to monitor a variety of analytes,e.g., lactate, and the like.

Analytes that may be monitored include, for example, acetyl choline,amylase, bilirubin, cholesterol, chorionic gonadotropin, creatine kinase(e.g., CK-MB), creatine, DNA, fructosamine, glucose, glutamine, growthhormones, hormones, ketones, lactate, peroxide, prostate-specificantigen, prothrombin, RNA, thyroid stimulating hormone, and troponin.The concentration of drugs, such as, for example, antibiotics (e.g.,gentamicin, vancomycin, and the like), digitoxin, digoxin, drugs ofabuse, theophylline, and warfarin, may also be monitored.

The analyte monitoring system 100 includes a sensor 101, a transmitterunit 102 coupled to the sensor 101, and a primary receiver unit 104which is configured to communicate with the transmitter unit 102 via acommunication link 103. The primary receiver unit 104 may be furtherconfigured to transmit data to a data processing terminal 105 forevaluating the data received by the primary receiver unit 104. Moreover,the data processing terminal 105 in one embodiment may be configured toreceive data directly from the transmitter unit 102 via a communicationlink which may optionally be configured for bi-directionalcommunication.

Also shown in FIG. 1 is a secondary receiver unit 106 which isoperatively coupled to the communication link 103 and configured toreceive data transmitted from the transmitter unit 102. Moreover, asshown in the Figure, the secondary receiver unit 106 is configured tocommunicate with the primary receiver unit 104 as well as the dataprocessing terminal 105. Indeed, the secondary receiver unit 106 may beconfigured for bi-directional wireless communication with each of theprimary receiver unit 104 and the data processing terminal 105. Asdiscussed in further detail below, in one embodiment of the presentinvention, the secondary receiver unit 106 may be configured to includea limited number of functions and features as compared with the primaryreceiver unit 104. As such, the secondary receiver unit 106 may beconfigured substantially in a smaller compact housing or embodied in adevice such as a wrist watch, for example. Alternatively, the secondaryreceiver unit 106 may be configured with the same or substantiallysimilar functionality as the primary receiver unit 104, and may beconfigured to be used in conjunction with a docking cradle unit forplacement by bedside, for night time monitoring, and/or bi-directionalcommunication device.

Only one sensor 101, transmitter unit 102, communication link 103, anddata processing terminal 105 are shown in the embodiment of the analytemonitoring system 100 illustrated in FIG. 1. However, it will beappreciated by one of ordinary skill in the art that the analytemonitoring system 100 may include one or more sensor 101, transmitterunit 102, communication link 103, and data processing terminal 105.Moreover, within the scope of the present invention, the analytemonitoring system 100 may be a continuous monitoring system, orsemi-continuous, or a discrete monitoring system. In a multi-componentenvironment, each device is configured to be uniquely identified by eachof the other devices in the system so that communication conflict isreadily resolved between the various components within the analytemonitoring system 100.

In one embodiment of the present invention, the sensor 101 is physicallypositioned in or on the body of a user whose analyte level is beingmonitored. The sensor 101 may be configured to continuously sample theanalyte level of the user and convert the sampled analyte level into acorresponding data signal for transmission by the transmitter unit 102.In one embodiment, the transmitter unit 102 is coupled to the sensor 101so that both devices are positioned on the user's body, with at least aportion of the analyte sensor 101 positioned transcutaneously under theskin layer of the user. The transmitter unit 102 performs dataprocessing such as filtering and encoding on data signals, each of whichcorresponds to a sampled analyte level of the user, for transmission tothe primary receiver unit 104 via the communication link 103.

In one embodiment, the analyte monitoring system 100 is configured as aone-way RF communication path from the transmitter unit 102 to theprimary receiver unit 104. In such embodiment, the transmitter unit 102transmits the sampled data signals received from the sensor 101 withoutacknowledgement from the primary receiver unit 104 that the transmittedsampled data signals have been received. For example, the transmitterunit 102 may be configured to transmit the encoded sampled data signalsat a fixed rate (e.g., at one minute intervals) after the completion ofthe initial power on procedure. Likewise, the primary receiver unit 104may be configured to detect such transmitted encoded sampled datasignals at predetermined time intervals. Alternatively, the analytemonitoring system 100 may be configured with a bidirectional RF (orotherwise) communication between the transmitter unit 102 and theprimary receiver unit 104.

Additionally, in one aspect, the primary receiver unit 104 may includetwo sections. The first section is an analog interface section that isconfigured to communicate with the transmitter unit 102 via thecommunication link 103. In one embodiment, the analog interface sectionmay include an RF receiver and an antenna for receiving and amplifyingthe data signals from the transmitter unit 102, which are thereafter,demodulated with a local oscillator and filtered through a band-passfilter. The second section of the primary receiver unit 104 is a dataprocessing section which is configured to process the data signalsreceived from the transmitter unit 102 such as by performing datadecoding, error detection and correction, data clock generation, anddata bit recovery.

In operation, upon completing the power-on procedure, the primaryreceiver unit 104 is configured to detect the presence of thetransmitter unit 102 within its range based on, for example, thestrength of the detected data signals received from the transmitter unit102 or a predetermined transmitter identification information. Uponsuccessful synchronization with the corresponding transmitter unit 102,the primary receiver unit 104 is configured to begin receiving from thetransmitter unit 102 data signals corresponding to the user's detectedanalyte level. More specifically, the primary receiver unit 104 in oneembodiment is configured to perform synchronized time hopping with thecorresponding synchronized transmitter unit 102 via the communicationlink 103 to obtain the user's detected analyte level.

Referring again to FIG. 1, the data processing terminal 105 may includea personal computer, a portable computer such as a laptop or a handhelddevice (e.g., personal digital assistants (PDAs)), and the like, each ofwhich may be configured for data communication with the receiver via awired or a wireless connection. Additionally, the data processingterminal 105 may further be connected to a data network (not shown) forstoring, retrieving and updating data corresponding to the detectedanalyte level of the user.

Within the scope of the present invention, the data processing terminal105 may include an infusion device such as an insulin infusion pump orthe like, which may be configured to administer insulin to patients, andwhich may be configured to communicate with the receiver unit 104 forreceiving, among others, the measured analyte level. Alternatively, thereceiver unit 104 may be configured to integrate an infusion devicetherein so that the receiver unit 104 is configured to administerinsulin therapy to patients, for example, for administering andmodifying basal profiles, as well as for determining appropriate bolusesfor administration based on, among others, the detected analyte levelsreceived from the transmitter unit 102.

Additionally, the transmitter unit 102, the primary receiver unit 104and the data processing terminal 105 may each be configured forbi-directional wireless communication such that each of the transmitterunit 102, the primary receiver unit 104 and the data processing terminal105 may be configured to communicate (that is, transmit data to andreceive data from) with each other via a wireless communication link.More specifically, the data processing terminal 105 may in oneembodiment be configured to receive data directly from the transmitterunit 102 via a communication link, where the communication link, asdescribed above, may be configured for bi-directional communication.

In this embodiment, the data processing terminal 105 which may includean insulin pump, may be configured to receive the analyte signals fromthe transmitter unit 102, and thus, incorporate the functions of thereceiver 104 including data processing for managing the patient'sinsulin therapy and analyte monitoring. In one embodiment, thecommunication link 103 may include one or more of an RF communicationprotocol, an infrared communication protocol, a Bluetooth® enabledcommunication protocol, an 802.11x wireless communication protocol, oran equivalent wireless communication protocol which would allow secure,wireless communication of several units (for example, per HIPAArequirements) while avoiding potential data collision and interference.

FIG. 2 is a block diagram of the transmitter of the data monitoring anddetection system shown in FIG. 1 in accordance with one embodiment ofthe present invention. Referring to the Figure, the transmitter unit 102in one embodiment includes an analog interface 201 configured tocommunicate with the sensor 101 (FIG. 1), a user input 202, and atemperature detection section 203, each of which is operatively coupledto a transmitter processor 204 such as a central processing unit (CPU).

Further shown in FIG. 2 are a transmitter serial communication section205 and an RF transmitter 206, each of which is also operatively coupledto the transmitter processor 204. Moreover, a power supply 207 such as abattery is also provided in the transmitter unit 102 to provide thenecessary power for the transmitter unit 102. Additionally, as can beseen from the Figure, clock 208 is provided to, among others, supplyreal time information to the transmitter processor 204.

As can be seen from FIG. 2, the sensor 101 (FIG. 1) is provided fourcontacts, three of which are electrodes—work electrode (W) 210, guardcontact (G) 211, reference electrode (R) 212, and counter electrode (C)213, each operatively coupled to the analog interface 201 of thetransmitter unit 102. In one embodiment, each of the work electrode (W)210, guard contact (G) 211, reference electrode (R) 212, and counterelectrode (C) 213 may be made using a conductive material that is eitherprinted or etched, for example, such as carbon which may be printed, ormetal foil (e.g., gold) which may be etched, or alternatively providedon a substrate material using laser or photolithography.

In one embodiment, a unidirectional input path is established from thesensor 101 (FIG. 1) and/or manufacturing and testing equipment to theanalog interface 201 of the transmitter unit 102, while a unidirectionaloutput is established from the output of the RF transmitter 206 of thetransmitter unit 102 for transmission to the primary receiver unit 104.In this manner, a data path is shown in FIG. 2 between theaforementioned unidirectional input and output via a dedicated link 209from the analog interface 201 to serial communication section 205,thereafter to the processor 204, and then to the RF transmitter 206. Assuch, in one embodiment, via the data path described above, thetransmitter unit 102 is configured to transmit to the primary receiverunit 104 (FIG. 1), via the communication link 103 (FIG. 1), processedand encoded data signals received from the sensor 101 (FIG. 1).Additionally, the unidirectional communication data path between theanalog interface 201 and the RF transmitter 206 discussed above allowsfor the configuration of the transmitter unit 102 for operation uponcompletion of the manufacturing process as well as for directcommunication for diagnostic and testing purposes.

As discussed above, the transmitter processor 204 is configured totransmit control signals to the various sections of the transmitter unit102 during the operation of the transmitter unit 102. In one embodiment,the transmitter processor 204 also includes a memory (not shown) forstoring data such as the identification information for the transmitterunit 102, as well as the data signals received from the sensor 101. Thestored information may be retrieved and processed for transmission tothe primary receiver unit 104 under the control of the transmitterprocessor 204. Furthermore, the power supply 207 may include acommercially available battery.

The transmitter unit 102 is also configured such that the power supplysection 207 is capable of providing power to the transmitter for aminimum of about three months of continuous operation after having beenstored for about eighteen months in a low-power (non-operating) mode. Inone embodiment, this may be achieved by the transmitter processor 204operating in low power modes in the non-operating state, for example,drawing no more than approximately 1 μA of current. Indeed, in oneembodiment, the final step during the manufacturing process of thetransmitter unit 102 may place the transmitter unit 102 in the lowerpower, non-operating state (i.e., post-manufacture sleep mode). In thismanner, the shelf life of the transmitter unit 102 may be significantlyimproved. Moreover, as shown in FIG. 2, while the power supply unit 207is shown as coupled to the processor 204, and as such, the processor 204is configured to provide control of the power supply unit 207, it shouldbe noted that within the scope of the present invention, the powersupply unit 207 is configured to provide the necessary power to each ofthe components of the transmitter unit 102 shown in FIG. 2.

Referring back to FIG. 2, the power supply section 207 of thetransmitter unit 102 in one embodiment may include a rechargeablebattery unit that may be recharged by a separate power supply rechargingunit (for example, provided in the receiver unit 104) so that thetransmitter unit 102 may be powered for a longer period of usage time.Moreover, in one embodiment, the transmitter unit 102 may be configuredwithout a battery in the power supply section 207, in which case thetransmitter unit 102 may be configured to receive power from an externalpower supply source (for example, a battery) as discussed in furtherdetail below.

Referring yet again to FIG. 2, the temperature detection section 203 ofthe transmitter unit 102 is configured to monitor the temperature of theskin near the sensor insertion site. The temperature reading is used toadjust the analyte readings obtained from the analog interface 201. TheRF transmitter 206 of the transmitter unit 102 may be configured foroperation in the frequency band of 315 MHz to 322 MHz, for example, inthe United States. Further, in one embodiment, the RF transmitter 206 isconfigured to modulate the carrier frequency by performing FrequencyShift Keying and Manchester encoding. In one embodiment, the datatransmission rate is 19,200 symbols per second, with a minimumtransmission range for communication with the primary receiver unit 104.

Referring yet again to FIG. 2, also shown is a leak detection circuit214 coupled to the guard contact (G) 211 and the processor 204 in thetransmitter unit 102 of the data monitoring and management system 100.The leak detection circuit 214 in accordance with one embodiment of thepresent invention may be configured to detect leakage current in thesensor 101 to determine whether the measured sensor data is corrupt orwhether the measured data from the sensor 101 is accurate.

FIG. 3 is a block diagram of the receiver/monitor unit of the datamonitoring and management system shown in FIG. 1 in accordance with oneembodiment of the present invention. Referring to FIG. 3, the primaryreceiver unit 104 includes a blood glucose test strip interface 301, anRF receiver 302, a user input 303, a temperature detection section 304,and a clock 305, each of which is operatively coupled to a receiverprocessor 307. As can be further seen from the Figure, the primaryreceiver unit 104 also includes a power supply 306 operatively coupledto a power conversion and monitoring section 308. Further, the powerconversion and monitoring section 308 is also coupled to the receiverprocessor 307. Moreover, also shown are a receiver serial communicationsection 309, and an output 310, each operatively coupled to the receiverprocessor 307.

In one embodiment, the test strip interface 301 includes a glucose leveltesting portion to receive a manual insertion of a glucose test strip,and thereby determine and display the glucose level of the test strip onthe output 310 of the primary receiver unit 104. This manual testing ofglucose can be used to calibrate sensor 101. The RF receiver 302 isconfigured to communicate, via the communication link 103 (FIG. 1) withthe RF transmitter 206 of the transmitter unit 102, to receive encodeddata signals from the transmitter unit 102 for, among others, signalmixing, demodulation, and other data processing. The input 303 of theprimary receiver unit 104 is configured to allow the user to enterinformation into the primary receiver unit 104 as needed. In one aspect,the input 303 may include one or more keys of a keypad, atouch-sensitive screen, or a voice-activated input command unit. Thetemperature detection section 304 is configured to provide temperatureinformation of the primary receiver unit 104 to the receiver processor307, while the clock 305 provides, among others, real time informationto the receiver processor 307.

Each of the various components of the primary receiver unit 104 shown inFIG. 3 is powered by the power supply 306 which, in one embodiment,includes a battery. Furthermore, the power conversion and monitoringsection 308 is configured to monitor the power usage by the variouscomponents in the primary receiver unit 104 for effective powermanagement and to alert the user, for example, in the event of powerusage which renders the primary receiver unit 104 in sub-optimaloperating conditions. An example of such sub-optimal operating conditionmay include, for example, operating the vibration output mode (asdiscussed below) for a period of time thus substantially draining thepower supply 306 while the processor 307 (thus, the primary receiverunit 104) is turned on. Moreover, the power conversion and monitoringsection 308 may additionally be configured to include a reverse polarityprotection circuit such as a field effect transistor (FET) configured asa battery activated switch.

The serial communication section 309 in the primary receiver unit 104 isconfigured to provide a bi-directional communication path from thetesting and/or manufacturing equipment for, among others,initialization, testing, and configuration of the primary receiver unit104. Serial communication section 309 can also be used to upload data toa computer, such as time-stamped blood glucose data. The communicationlink with an external device (not shown) can be made, for example, bycable, infrared (IR) or RF link. The output 310 of the primary receiverunit 104 is configured to provide, among others, a graphical userinterface (GUI) such as a liquid crystal display (LCD) for displayinginformation. Additionally, the output 310 may also include an integratedspeaker for outputting audible signals as well as to provide vibrationoutput as commonly found in handheld electronic devices, such as mobiletelephones presently available. In a further embodiment, the primaryreceiver unit 104 also includes an electro-luminescent lamp configuredto provide backlighting to the output 310 for output visual display indark ambient surroundings.

Referring back to FIG. 3, the primary receiver unit 104 in oneembodiment may also include a storage section such as a programmable,non-volatile memory device as part of the processor 307, or providedseparately in the primary receiver unit 104, operatively coupled to theprocessor 307. The processor 307 is further configured to performManchester decoding as well as error detection and correction upon theencoded data signals received from the transmitter unit 102 via thecommunication link 103.

In a further embodiment, the one or more of the transmitter unit 102,the primary receiver unit 104, secondary receiver unit 106, or the dataprocessing terminal/infusion section 105 may be configured to receivethe blood glucose value wirelessly over a communication link from, forexample, a glucose meter. In still a further embodiment, the user orpatient manipulating or using the analyte monitoring system 100 (FIG. 1)may manually input the blood glucose value using, for example, a userinterface (for example, a keyboard, keypad, and the like) incorporatedin the one or more of the transmitter unit 102, the primary receiverunit 104, secondary receiver unit 106, or the data processingterminal/infusion section 105.

Additional detailed description of the continuous analyte monitoringsystem, its various components including the functional descriptions ofthe transmitter are provided in U.S. Pat. No. 6,175,752 issued Jan. 16,2001 entitled “Analyte Monitoring Device and Methods of Use”, and inapplication Ser. No. 10/745,878 filed Dec. 26, 2003, now U.S. Pat. No.7,811,231, entitled “Continuous Glucose Monitoring System and Methods ofUse”, each assigned to the Assignee of the present application.

FIGS. 4A-4B illustrate a perspective view and a cross sectional view,respectively of an analyte sensor in accordance with one embodiment ofthe present invention. Referring to FIG. 4A, a perspective view of asensor 400, the major portion of which is above the surface of the skin410, with an insertion tip 430 penetrating through the skin and into thesubcutaneous space 420 in contact with the user's biofluid such asinterstitial fluid. Contact portions of a working electrode 401, areference electrode 402, and a counter electrode 403 can be seen on theportion of the sensor 400 situated above the skin surface 410. Workingelectrode 401, a reference electrode 402, and a counter electrode 403can be seen at the end of the insertion tip 430.

Referring now to FIG. 4B, a cross sectional view of the sensor 400 inone embodiment is shown. In particular, it can be seen that the variouselectrodes of the sensor 400 as well as the substrate and the dielectriclayers are provided in a stacked or layered configuration orconstruction. For example, as shown in FIG. 4B, in one aspect, thesensor 400 (such as the sensor 101 FIG. 1), includes a substrate layer404, and a first conducting layer 401 such as a carbon trace disposed onat least a portion of the substrate layer 404, and which may comprisethe working electrode. Also shown disposed on at least a portion of thefirst conducting layer 401 is a sensing layer 408.

Referring back to FIG. 4B, a first insulation layer such as a firstdielectric layer 405 is disposed or stacked on at least a portion of thefirst conducting layer 401, and further, a second conducting layer 409such as another carbon trace may be disposed or stacked on top of atleast a portion of the first insulation layer (or dielectric layer) 405.As shown in FIG. 4B, the second conducting layer 409 may comprise thereference electrode 402, and in one aspect, may include a layer ofsilver/silver chloride (Ag/AgCl).

Referring still again to FIG. 4B, a second insulation layer 406 such asa dielectric layer in one embodiment may be disposed or stacked on atleast a portion of the second conducting layer 409. Further, a thirdconducting layer 403 which may include carbon trace and that maycomprise the counter electrode 403 may in one embodiment be disposed onat least a portion of the second insulation layer 406. Finally, a thirdinsulation layer 407 is disposed or stacked on at least a portion of thethird conducting layer 403. In this manner, the sensor 400 may beconfigured in a stacked or layered construction or configuration suchthat at least a portion of each of the conducting layers is separated bya respective insulation layer (for example, a dielectric layer).

Additionally, within the scope of the present invention, some or all ofthe electrodes 401, 402, 403 may be provided on the same side of thesubstrate 404 in a stacked construction as described above, oralternatively, may be provided in a co-planar manner such that eachelectrode is disposed on the same plane on the substrate 404, however,with a dielectric material or insulation material disposed between theconducting layers/electrodes. Furthermore, in still another aspect ofthe present invention, the one or more conducting layers such as theelectrodes 401, 402, 403 may be disposed on opposing sides of thesubstrate 404.

Referring back to the Figures, in one embodiment, the transmitter unit102 (FIG. 1) is configured to detect the current signal from the sensor101 (FIG. 1) and the skin temperature near the sensor 101, which arepreprocessed by, for example, the transmitter processor 204 (FIG. 2) andtransmitted to the receiver unit (for example, the primary receiver unit104 (FIG. 1)) periodically at a predetermined time interval, such as forexample, but not limited to, once per minute, once every two minutes,once every five minutes, or once every ten minutes. Additionally, thetransmitter unit 102 may be configured to perform sensor insertionand/or removal detection and data quality analysis, informationpertaining to which are also transmitted to the receiver unit 104periodically at the predetermined time interval. In turn, the receiverunit 104 may be configured to perform, for example, skin temperaturecompensation as well as calibration of the sensor data received from thetransmitter 102.

For example, in one aspect, the transmitter unit 102 may be configuredto oversample the sensor signal at a nominal rate of four samples persecond, which allows the analyte anti-aliasing filter in the transmitterunit 102 to attenuate noise (for example, due to effects resulting frommotion or movement of the sensor after placement) at frequencies above 2Hz. More specifically, in one embodiment, the transmitter processor 204may be configured to include a digital filter to reduce aliasing noisewhen decimating the four Hz sampled sensor data to once per minutesamples for transmission to the receiver unit 104. As discussed infurther detail below, in one aspect, a two stage Kaiser Finite ImpulseResponse (FIR) filter may be used to perform the digital filtering foranti-aliasing. While Kaiser FIR filter may be used for digital filteringof the sensor signals, within the scope of the present disclosure, othersuitable filters may be used to filter the sensor signals.

In one aspect, the temperature measurement section 203 of thetransmitter unit 102 may be configured to measure once per minute the onskin temperature near the analyte sensor at the end of the minutesampling cycle of the sensor signal. Within the scope of the presentdisclosure, different sample rates may be used which may include, forexample, but are not limited to, measuring the on skin temperature foreach 30 second periods, each two minute periods, and the like.Additionally, as discussed above, the transmitter unit 102 may beconfigured to detect sensor insertion, sensor signal settling aftersensor insertion, and sensor removal, in addition to detecting forsensor—transmitter system failure modes and sensor signal dataintegrity. Again, this information is transmitted periodically by thetransmitter unit 102 to the receiver unit 104 along with the sampledsensor signals at the predetermined time intervals.

Referring again to the Figures, as the analyte sensor measurements areaffected by the temperature of the tissue around the transcutaneouslypositioned sensor 101, in one aspect, compensation of the temperaturevariations and affects on the sensor signals are provided fordetermining the corresponding glucose value. Moreover, the ambienttemperature around the sensor 101 may affect the accuracy of the on skintemperature measurement and ultimately the glucose value determined fromthe sensor signals. Accordingly, in one aspect, a second temperaturesensor is provided in the transmitter unit 102 away from the on skintemperature sensor (for example, physically away from the temperaturemeasurement section 203 of the transmitter unit 102), so as to providecompensation or correction of the on skin temperature measurements dueto the ambient temperature effects. In this manner, the accuracy of theestimated glucose value corresponding to the sensor signals may beattained.

In one aspect, the processor 204 of the transmitter unit 102 may beconfigured to include the second temperature sensor, and which islocated closer to the ambient thermal source within the transmitter unit102. In other embodiments, the second temperature sensor may be locatedat a different location within the transmitter unit 102 housing wherethe ambient temperature within the housing of the transmitter unit 102may be accurately determined.

Referring now to FIG. 5, in one aspect, an ambient temperaturecompensation routine for determining the on-skin temperature level foruse in the glucose estimation determination based on the signalsreceived from the sensor 101. Referring to FIG. 5, for each sampledsignal from the sensor 101, a corresponding measured temperatureinformation is received (510), for example, by the processor 204 fromthe temperature measurement section 203 (which may include, for example,a thermistor provided in the transmitter unit 102). In addition, asecond temperature measurement is obtained (520), for example, includinga determination of the ambient temperature level using a secondtemperature sensor provided within the housing of the transmitter unit102.

In one aspect, based on a predetermined ratio of thermal resistancesbetween the temperature measurement section 203 and the secondtemperature sensor (located, for example, within the processor 204 ofthe transmitter unit 102), and between the temperature measurementsection 203 and the skin layer on which the transmitter unit 102 isplaced and coupled to the sensor 101, ambient temperature compensationmay be performed (530), to determine the corresponding ambienttemperature compensated on skin temperature level (540). In oneembodiment, the predetermined ratio of the thermal resistances may beapproximately 0.2. However, within the scope of the present invention,this thermal resistance ratio may vary according to the design of thesystem, for example, based on the size of the transmitter unit 102housing, the location of the second temperature sensor within thehousing of the transmitter unit 102, and the like.

With the ambient temperature compensated on-skin temperatureinformation, the corresponding glucose value from the sampled analytesensor signal may be determined.

Referring again to FIG. 2, the processor 204 of the transmitter unit 102may include a digital anti-aliasing filter. Using analog anti-aliasingfilters for a one minute measurement data sample rate would require alarge capacitor in the transmitter unit 102 design, and which in turnimpacts the size of the transmitter unit 102. As such, in one aspect,the sensor signals may be oversampled (for example, at a rate of 4 timesper second), and then the data is digitally decimated to derive aone-minute sample rate.

As discussed above, in one aspect, the digital anti-aliasing filter maybe used to remove, for example, signal artifacts or otherwiseundesirable aliasing effects on the sampled digital signals receivedfrom the analog interface 201 of the transmitter unit 102. For example,in one aspect, the digital anti-aliasing filter may be used toaccommodate decimation of the sensor data from approximately four Hzsamples to one-minute samples. In one aspect, a two stage FIR filter maybe used for the digital anti-aliasing filter, which includes improvedresponse time, pass band and stop band properties.

Referring to FIG. 6, a routine for digital anti-aliasing filtering isshown in accordance with one embodiment. As shown, in one embodiment, ateach predetermined time period such as every minute, the analog signalfrom the analog interface 201 corresponding to the monitored analytelevel received from the sensor 101 (FIG. 1) is sampled (610). Forexample, at every minute, in one embodiment, the signal from the analoginterface 201 is over-sampled at approximately 4 Hz. Thereafter, thefirst stage digital filtering on the over-sampled data is performed(620), where, for example, a 1/6 down-sampling from 246 samples to 41samples is performed, and the resulting 41 samples is furtherdown-sampled at the second stage digital filtering (630) such that, forexample, a 1/41 down-sampling is performed from 41 samples (from thefirst stage digital filtering), to a single sample. Thereafter, thefilter is reset (640), and the routine returns to the beginning for thenext minute signal received from the analog interface 201.

While the use of FIR filter, and in particular the use of Kaiser FIRfilter, is within the scope of the present invention, other suitablefilters, such as FIR filters with different weighting schemes orInfinite Impulse Response (IIR) filters, may be used.

Referring yet again to the Figures, the transmitter unit 102 may beconfigured in one embodiment to periodically perform data quality checksincluding error condition verifications and potential error conditiondetections, and also to transmit the relevant information related to oneor more data quality, error condition or potential error conditiondetection to the receiver unit 104 with the transmission of themonitored sensor data. For example, in one aspect, a state machine maybe used in conjunction with the transmitter unit 102 and which may beconfigured to be updated four times per second, the results of which aretransmitted to the receiver unit 104 every minute.

In particular, using the state machine, the transmitter unit 102 may beconfigured to detect one or more states that may indicate when a sensoris inserted, when a sensor is removed from the user, and further, mayadditionally be configured to perform related data quality checks so asto determine when a new sensor has been inserted or transcutaneouslypositioned under the skin layer of the user and has settled in theinserted state such that the data transmitted from the transmitter unit102 does not compromise the integrity of signal processing performed bythe receiver unit 104 due to, for example, signal transients resultingfrom the sensor insertion.

That is, when the transmitter unit 102 detects low or no signal from thesensor 101, which is followed by detected signals from the sensor 101that is above a given signal, the processor 204 may be configured toidentify such transition is monitored signal levels and associate with apotential sensor insertion state. Alternatively, the transmitter unit102 may be configured to detect the signal level above the otherpredetermined threshold level, which is followed by the detection of thesignal level from the sensor 101 that falls below the same or anotherpredetermined threshold level. In such a case, the processor 204 may beconfigured to associate or identify such transition or condition in themonitored signal levels as a potential sensor removal state.

Accordingly, when either of potential sensor insertion state orpotential sensor removal state, or any other state, is detected by thetransmitter unit 102, this information is transmitted to the receiverunit 104, and in turn, the receiver unit may be configured to prompt theuser for confirmation of either of the detected potential sensor relatedstates. In one aspect, the current state information is continuously orintermittently transmitted to the receiver unit, for example, when thereis a failed transmission (for example, a missed data packet from thetransmitter to the receiver unit), and the current state information isknown by the receiver so as to determine the state transition. Inanother aspect, the sensor insertion state or potential sensor removalstate may be detected or determined by the receiver unit based on one ormore signals received from the transmitter unit 102.

For example, in one aspect, the transmitter unit may be coupled to oneor more sensors, each sensor configured to generate one or more signalsassociated with the analyte being monitored. Alternatively, the receiverunit may be coupled, wirelessly or otherwise, to one or moretransmitters, each with their own sensor signal. In another aspect, thesensor/transmitter configuration may include a mechanism to detectconnection between the sensor/transmitter, and/or sensor implantation inthe patient's tissue. For instance, a conductivity loop may beincorporated into the sensor/transmitter configuration, such that anelectrically conductive path is provided along the sensor length with anopening at the portion of the sensor that is located in the patient'sanalyte being monitored, and a return path provided along the sensorlength, with two contacts formed to meet with two contacts on thetransmitter. The transmitter may be configured to apply electricalcurrent to the contacts and detect current flow when a) both contactsare in electrical contact with the sensor contacts, and b) the sensor ispositioned properly in the analyte being monitored, closing theelectrical circuit with a finite resistance that allows detectablecurrent to flow.

The transmitter and/or receiver unit may be designed to use thisdetected signal alone or in combination with the sensor signal todetermine the operational state of the sensor. In another aspect, theconductive path may be provided so that it indicates the contact betweenthe sensor and the transmitter, and not configured to pass along thelength of the sensor. Again, the transmitter and/or receiver may beconfigured to use this signal alone or in combination with the sensorsignal to determine the operational state of the sensor. In yet anotherembodiment, a magnetic detection mechanism may be provided to detectsensor/transmitter connection where the transmitter unit may beconfigured to electromagnetically detect a magnet located in the sensorwhen in close proximately thereto.

In another aspect, the sensor insertion state or potential sensorremoval state may be detected or determined by the receiver unit basedon one or more signals from the transmitter unit 102 and one or moresignals derived at the receiver unit 104. For example, similar to analarm condition or a notification to the user, the receiver unit 104 maybe configured to display a request or a prompt on the display or anoutput unit of the receiver unit 104 a text and/or other suitablenotification message to inform the user to confirm the state of thesensor 101.

For example, the receiver unit 104 may be configured to display thefollowing message: “New Sensor Inserted” or “Did you insert a newSensor?” or a similar notification in the case where the receiver unit104 receives one or more signals from the transmitter unit 102associated with the detection of the signal level below thepredetermined threshold level for the predefined period of time,followed by the detection of the signal level from the sensor 101 aboveanother predetermined threshold level for another predefined period oftime. Alternatively, the receiver unit may display this message when itreceives the “new sensor” or “sensor inserted” operational state datafrom the transmitter, that has changed from the previous operationalstate data, stored in the receiver unit, indicating “sensor removed”.Indeed, in one aspect, the receiver unit may be configured to maintain astate machine, and if it is in the “sensor removed” state, the receiveris configured to look for “new sensor” or “sensor stable” transitions todetermine if it needs to change state.

Additionally, the receiver unit 104 may be configured to display thefollowing message: “Sensor removed” or “Did you remove the sensor?” or asimilar notification in the case where the receiver unit 104 receivedone or more signals from the transmitter unit 102 associated with thedetection of the signal level from the sensor 101 that is above theother predetermined threshold level for the other predefined period oftime, which is followed by the detection of the signal level from thesensor 101 that falls below the predetermined threshold level for thepredefined period of time. Again, in another embodiment, the receiverunit may display this message when it receives the “sensor removed”operational state data from the transmitter, that has changed from theprevious operational state data, stored in the receiver unit, indicating“new sensor” or “sensor inserted”.

Based on the user confirmation received, the receiver unit 104 may befurther configured to execute or perform additional related processingand routines in response to the user confirmation or acknowledgement.For example, when the user confirms, using the user interfaceinput/output mechanism of the receiver unit 104, for example, that a newsensor has been inserted, the receiver unit 104 may be configured toinitiate a new sensor insertion related routine including, such as, forexample, a sensor calibration routine including, for example,calibration timer, sensor expiration timer and the like. Alternatively,when the user confirms or it is determined that the sensor 101 is notproperly positioned or otherwise removed from the insertion site, thereceiver unit 104 may be accordingly configured to perform relatedfunctions such as, for example, stop displaying of the glucosevalues/levels, or deactivating the alarm monitoring conditions.

On the other hand, in response to the potential sensor insertionnotification generated by the receiver unit 104, if the user confirmsthat no new sensor has been inserted, then the receiver unit 104 in oneembodiment is configured to assume that the sensor 101 is in acceptableoperational state, and continues to receive and process signals from thetransmitter unit 102.

In this manner, in cases, for example, when there is momentary movementor temporary dislodging of the sensor 101 from the initially positionedtranscutaneous state, or when one or more of the contact points betweensensor 101 and the transmitter unit 102 are temporarily disconnected,but otherwise, the sensor 101 is operational and within its useful life,the routine above provides an option to the user to maintain the usageof the sensor 101, to not replace the sensor 101 prior to the expirationof its useful life. In this manner, in one aspect, false positiveindications of sensor 101 failure may be identified and addressed.

For example, FIG. 7 is a flowchart illustrating actual or potentialsensor insertion or removal detection routine in accordance with oneembodiment of the present invention. Referring to the Figure, the statemachine is in an initial operational state, for instance, the “sensorremoved” state. Next, the current analyte related signal is received andthen compared to one or more predetermined signal characteristics. Onepredetermined signal characteristic, associated with new sensorinsertion, is for the signal level to exceed 18 ADC (analog to digitalconversion) counts continuously for approximately 10 seconds. Anotherpredetermined signal characteristic, associated with signal settling(that is, the signal transient associated with sensor insertion hassubsided), is for the signal level to exceed 9 ADC counts and the resultof the current signal minus a previous signal from 10 seconds prior,retrieved from storage, must be less than 59 ADC counts, bothcontinuously for a duration of 90 seconds.

Another predetermined signal characteristic, associated with sensorremoval, is for the signal level to be less than 9 ADC countscontinuously for 10 seconds. It is to be noted that other values forlevels and durations may be contemplated to be more suitable for variousdesigns and are within the scope of the present disclosure. Also, inparticular embodiments, the signal characteristic criteria may allow oneor more violations of the signal threshold or rate deviances (such asexceeding the threshold or rate). Also, the duration may be variable,where that duration and threshold is determined by some othercharacteristic, such as present operational state. Other variations insignal characteristics may be contemplated based on the detectability ofother contemplated operational states or on the previously discussedoperational states. Also, prefiltering of the signals may be includedprior to the comparison with predetermined signal characteristics, asappropriate.

Referring back to the Figure, a new operational state is determined. Inone aspect this is based on the present operational state, and theresults from the signal being compared with predetermined signalcharacteristics. For example, if the present operational state is“sensor removed”, and result of the predetermined signal characteristiccomparison associated with new sensor insertion is true, then theoperational state will transition to the “new sensor” state. Likewise,if the present operational state is “sensor inserted” or “new sensor”,and the result of the predetermined signal characteristic comparisonassociated with sensor removal is true, then the operational state willtransition to the “sensor removed” state. If the comparison results arefalse, then the operational state stays unchanged. Similarly, otherstate transition operations can be contemplated and implemented asrequired.

In yet another aspect, based on the present operational state, onlypredetermined signal characteristics relevant to that operational statemay be compared with the signal. Also, data quality status, asdetermined upon every received new signal, may alter the statetransition operation. For instance, state transitions may be precludedif it is determined that data quality is invalid, and not allowed untildata quality is determined to be valid.

In this manner, in one aspect of the present invention, based on atransition state of the received analyte related signals, it may bepossible to determine the state of the analyte sensor, and based onwhich the user or the patient to confirm whether the analyte sensor isin the desired or proper position, has been temporarily dislocated, orotherwise, removed from the desired insertion site so as to require anew analyte sensor.

In this manner, in one aspect, when the monitored signal from the sensor101 crosses a transition level (for example, from no or low signal levelto a high signal level, or vice versa), the transmitter unit 102 may beconfigured to generate an appropriate output data associated with thesensor signal transition, for transmission to the receiver unit 104(FIG. 1). Additionally, as discussed in further detail below, in anotherembodiment, the determination of whether the sensor 101 has crossed atransition level may be determined by the receiver/monitor unit 104/106based, at least in part, on the one or more signals received from thetransmitter unit 102.

FIG. 8 is a flowchart illustrating receiver unit processingcorresponding to the actual or potential sensor insertion or removaldetection routine of FIG. 7 in accordance with one embodiment of thepresent invention. Referring now to FIG. 8, when the receiver unit 104receives the generated output data from the transmitter unit 102 (810),it is related to a corresponding operation state such as a potential newoperational state of the sensor 101 (820). Moreover, if the potentialnew operational state is different than the current operational state, anotification associated with the sensor operation state is generated andoutput to the user on the display unit or any other suitable outputsegment of the receiver unit 104 (830). When a user input signal isreceived in response to the notification associated with the sensorstate operation state (840), the receiver unit 104 is configured toexecute one or more routines associated with the received user inputsignal (850).

That is, as discussed above, in one aspect, if the user confirms thatthe sensor 101 has been removed, the receiver unit 104 may be configuredto terminate or deactivate alarm monitoring and glucose displayingfunctions. On the other hand, if the user confirms that a new sensor 101has been positioned or inserted into the user, then the receiver unit104 may be configured to initiate or execute routines associated withthe new sensor insertion, such as, for example, calibration procedures,establishing calibration timer, and establishing sensor expirationtimer.

In a further embodiment, based on the detected or monitored signaltransition, the receiver/monitor unit may be configured to determine thecorresponding sensor state without relying upon the user input orconfirmation signal associated with whether the sensor is dislocated orremoved from the insertion site, or otherwise, operating properly.

FIG. 9 is a flowchart illustrating data processing corresponding to theactual or potential sensor insertion or removal detection routine inaccordance with another embodiment of the present invention. Referringto FIG. 9, a current analyte related signal is received from thetransmitter unit and compared to a predetermined signal characteristic(910). Thereafter, a new potential operational state associated with ananalyte monitoring device such as, for example, the sensor 101 (FIG. 1)is retrieved (920) from a storage unit or otherwise resident in, forexample, a memory of the receiver/monitor unit. Additionally, a prioranalyte related signal is also retrieved from the storage unit, andcompared to the current analyte related signal received (930). An outputdata is generated which is associated with the operational state, andwhich, at least in part, is based on the one or more of the receivedcurrent analyte related signal and the retrieved prior analyte relatedsignal (940).

Referring again to FIG. 9, when the new potential operational state isgenerated, a corresponding user input command or signal is received inresponse to the generated and output data (950), and which may includeone or more of a confirmation, verification, or rejection of theoperational state related to the analyte monitoring device.

FIG. 10 is a flowchart illustrating a concurrent passive notificationroutine in the data receiver/monitor unit of the data monitoring andmanagement system of FIG. 1 in accordance with one embodiment of thepresent invention. Referring to FIG. 10, a predetermined routine isexecuted (1010). During the execution of the predetermined routine, analarm condition is detected (1020), and when the alarm or alertcondition is detected, a first indication associated with the detectedalarm or alert condition is output concurrent to the execution of thepredetermined routine (1030).

That is, in one embodiment, when a predefined routine is being executed,and an alarm or alert condition is detected, a notification is providedto the user or patient associated with the detected alarm or alertcondition, but which does not interrupt or otherwise disrupt theexecution of the predefined routine. Referring back to FIG. 10, upontermination of the predetermined routine, another output or secondindication associated with the detected alarm condition is output ordisplayed (1040).

More specifically, in one aspect, the user interface notificationfeature associated with the detected alarm condition is output to theuser only upon the completion of an ongoing routine which was in theprocess of being executed when the alarm condition is detected. Asdiscussed above, when such alarm condition is detected during theexecution of a predetermined routine, a temporary alarm notificationsuch as, for example, a backlight indicator, a text output on the userinterface display, a reverse-video flashing of text, icon, a newlydisplayed flashing bar, or any other suitable output indication may beprovided to alert the user or the patient of the detected alarmcondition substantially in real time, but which does not disrupt anongoing routine.

Within the scope of the present invention, the ongoing routine or thepredetermined routine being executed may include one or more ofperforming a finger stick blood glucose test (for example, for purposesof periodically calibrating the sensor 101), or any other processes thatinterface with the user interface, for example, on the receiver/monitorunit 104/106 (FIG. 1) including, but not limited to, the configurationof device settings, review of historical data such as glucose data,alarms, events, entries in the data log, visual displays of dataincluding graphs, lists, and plots, data communication managementincluding RF communication administration, data transfer to the dataprocessing terminal 105 (FIG. 1), or viewing one or more alarmconditions with a different priority in a preprogrammed or determinedalarm or notification hierarchy structure.

In this manner, in one aspect of the present invention, the detection ofone or more alarm conditions may be presented or notified to the user orthe patient, without interrupting or disrupting an ongoing routine orprocess in, for example, the receiver/monitor unit 104/106 of the datamonitoring and management system 100 (FIG. 1).

A method in accordance with one embodiment includes detecting a firsttemperature related signal from a first source, detecting a secondtemperature related signal from a second source, the second sourcelocated at a predetermined distance from the first source, andestimating an analyte temperature related signal based on the first andsecond detected temperature signals.

The first source in one aspect may be located substantially in closeproximity to a transcutaneously positioned analyte sensor, and morespecifically, in one embodiment, the first source may be locatedapproximately 0.75 inches from the analyte sensor.

In a further embodiment, the analyte temperature related signal may beestimated based on a predetermined value associated with the detectedfirst and second temperature related signals, where the predeterminedvalue may include a ratio of thermal resistances associated with thefirst and second sources.

The method in a further aspect may include determining a glucose valuebased on the estimated analyte temperature related signal and amonitored analyte level.

The second temperature related signal in yet another aspect may berelated to an ambient temperature source.

An apparatus in a further embodiment may include a housing, an analytesensor coupled to the housing and transcutaneously positionable under askin layer of a user, a first temperature detection unit coupled to thehousing configured to detect a temperature associated with the analytesensor, and a second temperature detection unit provided in the housingand configured to detect an ambient temperature.

The one or more of the first temperature detection unit or the secondtemperature detection unit may include one or more of a thermistor, asemiconductor temperature sensor, or a resistance temperature detector(RTD).

The apparatus in a further aspect may also include a processor, where atleast a portion of the second temperature detection unit may be providedwithin the processor.

In another embodiment, the processor may be configured to receive thetemperature associated with the analyte sensor, the ambient temperature,and an analyte related signal from the analyte sensor, and also, theprocessor may be configured to estimate an analyte temperature relatedsignal based on the temperature associated with the analyte sensor, andthe ambient temperature.

Also, the processor may be configured to determine a glucose value basedon the estimated analyte temperature related signal and an analyterelated signal from the analyte sensor.

In still another aspect, the analyte temperature related signal may beestimated based on a predetermined value associated with the detectedtemperature associated with the analyte sensor, and the ambienttemperature, where the predetermined value may include a ratio ofthermal resistances associated with the temperature associated with theanalyte sensor, and the ambient temperature.

Alternatively, the predetermined value in still another aspect may bevariable based on error feedback signal associated with the monitoredanalyte level by the analyte sensor, where the error feedback signal maybe associated with a difference between a blood glucose reference valueand the analyte sensor signal.

The apparatus may also include a transmitter unit configured to transmitone or more signals associated with the detected temperature associatedwith the analyte sensor, detected ambient temperature, an analyterelated signal from the analyte sensor, analyte temperature relatedsignal based on the temperature associated with the analyte sensor, andthe ambient temperature, or a glucose value based on the estimatedanalyte temperature related signal and the analyte related signal fromthe analyte sensor.

The transmitter unit may include an RF transmitter.

A system in accordance with still another embodiment may include a datareceiver configured to receive a first temperature related signal from afirst source, a second temperature related signal from a second source,the second source located at a predetermined distance from the firstsource, and a processor operatively coupled to the data receiver, andconfigured to estimate an analyte temperature related signal based onthe first and second detected temperature signals.

An apparatus in accordance with a further embodiment includes a digitalfilter unit including a first filter stage and a second filter stage,the digital filter unit configured to receive a sampled signal, wherethe first filter stage is configured to filter the sampled signal basedon a first predetermined filter characteristic to generate a firstfilter stage output signal, and further, where the second filter stageis configured to filter the first filter stage output signal based on asecond predetermined filter characteristic to generate an output signalassociated with a monitored analyte level.

The sampled signal may include an over-sampled signal at a frequency ofapproximately 4 Hz.

The digital filter unit may include one of a Finite Impulse Response(FIR) filter, or an Infinite Impulse Response (IIR) filter.

The first and the second filter stages may include a respective firstand second down sampling filter characteristics.

Also, the one or more of the first and second filter stages may includedown sampling the sampled signal or the first filter stage outputsignal, respectively, where the received sampled signal may beassociated with the monitored analyte level of a user.

In another aspect, the digital filter unit may be configured to receivethe sampled signal at a predetermined time interval.

The predetermined time interval in one aspect may include one ofapproximately 30 second, approximately one minute, approximately twominutes, approximately five minutes, or any other suitable time periods.

A method in accordance with yet another embodiment includes receiving asampled signal associated with a monitored analyte level of a user,performing a first stage filtering based on the received sampled signalto generate a first stage filtered signal, performing a second stagefiltering based on the generated first stage filtered signal, andgenerating a filtered sampled signal.

The sampled signal may include an over-sampled signal at a frequency ofapproximately 4 Hz, and also, where the first and the second stagefiltering may include a respective first and second down sampling basedon one or more filter characteristics.

The received sampled signal in one aspect may be periodically receivedat a predetermined time interval, where the predetermined time intervalmay include one of approximately 30 second, approximately one minute,approximately two minutes, or approximately five minutes.

A method in still another embodiment may include receiving a signalassociated with an analyte level of a user, determining whether thereceived signal deviates from a predetermined signal characteristic,determining an operational state associated with an analyte monitoringdevice, comparing a prior signal associated with the analyte level ofthe user to the received signal, generating an output data associatedwith the operational state of the analyte monitoring device based on oneor more of the received signal and the prior signal.

The predetermined signal characteristic in one embodiment may include asignal level transition from below a first predetermined level to abovethe first predetermined level, a signal level transition from above asecond predetermined level to below the second predetermined threshold,a transition from below a predetermined signal rate of change thresholdto above the predetermined signal rate of change threshold, or atransition from above the predetermined signal rate of change thresholdto below the predetermined signal rate of change threshold.

In one aspect, the first predetermined level and the secondpredetermined level each may include one of approximately 9 ADC countsor approximately 18 ADC counts, or any other suitable signal levels oranalog to digital converter (ADC) counts that respectively represent orcorrespond to a no sensor signal state, a sensor signal state, or thelike.

The predetermine signal characteristic may include in one aspect, atransition from below a predetermined level to above and wherein thesignal is maintained above the predetermined level for a predeterminedperiod of time, where the predetermined period of time may include oneof approximately 10 seconds, 30 seconds, or less than 30 seconds, orgreater than 30 seconds, or any other suitable time periods.

In a further aspect, the operational state may include a no detectedsensor state, or a sensor presence state.

The output data in one embodiment may include a user notification alert.

Further, the output data may include an indicator to start one or moreprocessing timers associated with a respective one or more dataprocessing routines, where the one or more processing timers may includea respective one of a calibration timer, or a sensor expiration timer.

The method may include receiving a user input data based on the outputdata, where the user input data may include a user confirmation of oneof the change in operational state or no change in operational state.

The method may further include modifying the operational state, wherethe operational state may be modified based on one of the received userinput data, or based on the generated output data.

The method may include presenting the output data, where presenting theoutput data may include one or more of visually presenting the outputdata, audibly presenting the output data, vibratorily presenting theoutput data, or one or more combinations thereof.

The analyte level may include glucose level of the user.

The operational state may include one of an analyte sensor removalstate, an analyte sensor insertion state, an analyte sensor dislocationstate, an analyte sensor insertion with an associated transient signalstate, or an analyte sensor insertion with an associated stabilizedsignal state.

An apparatus in still yet another embodiment may include a dataprocessing unit including a data processor configured to determinewhether a received signal associated with an analyte level of a userdeviates from a predetermined signal characteristic, determine anoperational state associated with an analyte monitoring device, comparea prior signal associated with the analyte level of the user to thereceived signal, and generate an output data associated with theoperational state of the analyte monitoring device based on one or moreof the received signal or the prior signal.

The data processing unit may include a communication unit operativelycoupled to the data processor and configured to communicate one or moreof the received signal, the prior signal, and the output data associatedthe operational state of the analyte monitoring device.

The communication unit may include one of an RF transmitter, an RFreceiver, an infrared data communication device, a Bluetooth® datacommunication device, or a Zigbee® data communication device.

The data processing unit may include a storage unit operatively coupledto the data processor to store one or more of the received signalassociated with the analyte level, the predetermined signalcharacteristic, the operational state associated with the analytemonitoring device, the prior signal associated with the analyte level ofthe user, or the output data associated with the operational state ofthe analyte monitoring device.

A method in accordance with still yet a further embodiment may includereceiving a signal associated with an analyte level of a user,determining whether the received signal deviates from a predeterminedsignal characteristic, determining an operational state associated withan analyte monitoring device, comparing a prior signal associated withthe analyte level of the user to the received signal, presenting anoutput data associated with the operational state of the analytemonitoring device based, at least in part, on one or more of thereceived signal or the prior signal, and receiving a user input databased on the presented output data.

In still another aspect, the predetermined signal characteristic mayinclude a signal level transition from below a first predetermined levelto above the first predetermined level, a signal level transition fromabove a second predetermined level to below the second predeterminedlevel, a transition from below a predetermined signal rate of changethreshold to above the predetermined signal rate of change threshold,and a transition from above the predetermined signal rate of changethreshold to below the predetermined signal rate of change threshold,and further, where the first predetermined level and the secondpredetermined level each may include one of approximately 9 ADC countsor approximately 18 ADC counts, or other predetermined ADC counts orsignal levels.

The predetermine signal characteristic in another aspect may include atransition from below a predetermined level to above and wherein thesignal is maintained above the predetermined level for a predeterminedperiod of time which may include, for example, but not limited to,approximately 10 seconds, 30 seconds, or less than 30 seconds, orgreater than 30 seconds.

Further, the operational state may include a no detected sensor state,or a sensor presence state.

Moreover, the output data may include a user notification alert.

The output data may include an indicator to start one or more processingtimers associated with a respective one or more data processingroutines, where the one or more processing timers may include arespective one of a calibration timer, or a sensor expiration timer.

In another aspect, the user input data may include a user confirmationof one of the change in operational state or no change in operationalstate.

The method may include modifying the operational state based on, forexample, one of the received user input data, or based on the generatedoutput data.

Additionally, presenting the output data may include one or more ofvisually presenting the output data, audibly presenting the output data,vibratorily presenting the output data, or one or more combinationsthereof.

Also, the operational state may include one of an analyte sensor removalstate, an analyte sensor insertion state, an analyte sensor dislocationstate, an analyte sensor insertion with an associated transient signalstate, or an analyte sensor insertion with an associated stabilizedsignal state.

A data processing device in accordance with one embodiment may include auser interface unit, and a data processor operatively coupled to theuser interface unit, the data processor configured to receive a signalassociated with an analyte level of a user, determine whether thereceived signal deviates from a predetermined signal characteristic,determine an operational state associated with an analyte monitoringdevice, compare a prior signal associated with the analyte level of theuser to the received signal, present in the user interface unit anoutput data associated with the operational state of the analytemonitoring device based, at least in part, on one or more of thereceived signal or the prior signal, and to receive a user input datafrom the user interface unit based on the presented output data.

The user interface unit in one aspect may include one or more of a userinput unit, a visual display unit, an audible output unit, a vibratoryoutput unit, or a touch sensitive user input unit.

In one embodiment, the device may include a communication unitoperatively coupled to the data processor and configured to communicateone or more of the received signal, the prior signal, and the outputdata associated with the operational state of the analyte monitoringdevice, where the communication unit may include, for example, but notlimited to one of an RF transmitter, an RF receiver, an infrared datacommunication device, a Bluetooth® data communication device, a Zigbee®data communication device, or a wired connection.

The data processing device may include a storage unit operativelycoupled to the data processor to store one or more of the receivedsignal associated with the analyte level, the predetermined signalcharacteristic, the operational state associated with the analytemonitoring device, the prior signal associated with the analyte level ofthe user, or the output data associated with the operational state ofthe analyte monitoring device.

A method in accordance with still yet another embodiment may includeexecuting a predetermined routine associated with an operation of ananalyte monitoring device, detecting one or more predefined alarmconditions associated with the analyte monitoring device, outputting afirst indication associated with the detected one or more predefinedalarm conditions during the execution of the predetermined routine,outputting a second indication associated with the detected one or morepredefined alarm conditions after the execution of the predeterminedroutine, where the predetermined routine is executed withoutinterruption during the outputting of the first indication.

In one aspect, the predetermined routine may include one or moreprocesses associated with performing a blood glucose assay, one or moreconfiguration settings, analyte related data review or analysis, datacommunication routine, calibration routine, or reviewing a higherpriority alarm condition notification compared to the predeterminedroutine, or any other process or routine that requires the userinterface.

Moreover, in one aspect, the first indication may include one or more ofvisual, audible, or vibratory indicators.

Further, the second indication may include one or more of visual,audible, or vibratory indicators.

In one aspect, the first indication may include a temporary indicator,and further, and the second indication may include a predetermined alarmassociated with detected predefined alarm condition.

In still another aspect, the first indication may be active during theexecution of the predetermined routine, and may be inactive at the endof the predetermined routine.

Further, the second indication in a further aspect may be active at theend of the predetermined routine.

Moreover, each of the first indication and the second indication mayinclude one or more of a visual text notification alert, a backlightindicator, a graphical notification, an audible notification, or avibratory notification.

The predetermined routine may be executed to completion withoutinterruption.

An apparatus in accordance with still another embodiment may include auser interface, and a data processing unit operatively coupled to theuser interface, the data processing unit configured to execute apredetermined routine associated with an operation of an analytemonitoring device, detect one or more predefined alarm conditionsassociated with the analyte monitoring device, output on the userinterface a first indication associated with the detected one or morepredefined alarm conditions during the execution of the predeterminedroutine, and output on the user interface a second indication associatedwith the detected one or more predefined alarm conditions after theexecution of the predetermined routine, wherein the predeterminedroutine is executed without interruption during the outputting of thefirst indication.

The predetermined routine may include one or more processes associatedwith performing a blood glucose assay, one or more configurationsettings, analyte related data review or analysis, data communicationroutine, calibration routine, or reviewing a higher priority alarmcondition notification compared to the predetermined routine.

The first indication or the second indication or both, in one aspect mayinclude one or more of visual, audible, or vibratory indicators outputon the user interface.

In addition, the first indication may include a temporary indicator, andfurther, wherein the second indication includes a predetermined alarmassociated with detected predefined alarm condition.

Also, the first indication may be output on the user interface duringthe execution of the predetermined routine, and is not output on theuser interface at or prior to the end of the predetermined routine.

Additionally, the second indication may be active at the end of thepredetermined routine.

In another aspect, each of the first indication and the secondindication may include a respective one or more of a visual textnotification alert, a backlight indicator, a graphical notification, anaudible notification, or a vibratory notification, configured to outputon the user interface.

Various other modifications and alterations in the structure and methodof operation of this invention will be apparent to those skilled in theart without departing from the scope and spirit of the invention.Although the invention has been described in connection with specificpreferred embodiments, it should be understood that the invention asclaimed should not be unduly limited to such specific embodiments. It isintended that the following claims define the scope of the presentinvention and that structures and methods within the scope of theseclaims and their equivalents be covered thereby.

What is claimed is:
 1. A method, comprising: receiving a signalassociated with a monitored analyte level; retrieving a prior signalassociated with an analyte monitoring device; analyzing the prior signaland the received signal based on a predetermined signal characteristicincluding a determination of the received signal below a predeterminedlevel after a determination of the prior signal above a predeterminedthreshold; generating an output data based at least in part on theanalysis of the prior signal and the received signal; and transitioningfrom a sensor insertion state to a sensor removal state associated withthe analyte monitoring device based at least in part upon a response tothe output data.
 2. The method of claim 1, wherein the predeterminedsignal characteristic includes a determination of a plurality of priorsignals above the predetermined level.
 3. The method of claim 2, whereinthe predetermined level includes one of approximately 9 ADC counts orapproximately 18 ADC counts.
 4. The method of claim 2, wherein thepredetermined signal characteristic includes a determination of thepredetermined number of prior signals above the predetermined level fora second predetermined time period.
 5. The method of claim 1, whereinthe predetermined signal characteristic includes a signal transitionfrom above the predetermined level to below the predetermined level. 6.The method of claim 1, wherein the output data includes a notificationalert.
 7. The method of claim 1, wherein the output data includes anindicator to start one or more processing timers associated with arespective one or more data processing routines.
 8. The method of claim7, wherein the one or more processing timers includes a respective oneof a calibration timer, or a sensor expiration timer.
 9. The method ofclaim 1, including presenting the output data.
 10. The method of claim9, wherein presenting the output data includes one or more of visuallypresenting the output data, audibly presenting the output data,vibratorily presenting the output data, or one or more combinationsthereof.
 11. The method of claim 1, wherein the analyte level includes amonitored glucose level.
 12. The method of claim 1, wherein thepredetermined signal characteristic includes a determination of apredetermined number of received signals below the predetermined level.13. The method of claim 12, wherein the predetermined signalcharacteristic includes the determination of the predetermined number ofreceived signals below the predetermined level for a first predeterminedtime period.
 14. The method of claim 13, wherein the first predeterminedperiod of time includes one of approximately 10 seconds, 30 seconds,less than 30 seconds, or greater than 30 seconds.
 15. The method ofclaim 13 wherein the predetermined signal characteristic furtherincludes a determination of a predetermined number of prior signalsabove the predetermined level for a second predetermined time period.16. An apparatus, comprising a data processing unit including a dataprocessor configured to receive a signal associated with a monitoredanalyte level, retrieve a prior signal associated with an analytemonitoring device, analyze the prior signal and the received signalbased on a predetermined signal characteristic including a determinationof the received signal below a predetermined level after a determinationof the prior signal above a predetermined threshold, generate an outputbased at least in part on the analysis of the prior signal and thereceived signal, and transition from a sensor insertion state to asensor removal state associated with the analyte monitoring device basedat least in part upon a response to output data.
 17. The apparatus ofclaim 16, wherein the data processing unit includes a communication unitoperatively coupled to the data processor and configured to communicateone or more of the received signal, the prior signal, and the outputdata.
 18. The apparatus of claim 17, wherein the communication unitincludes one of an RF transmitter, an RF receiver, an infrared datacommunication device, or a short-range data communication device. 19.The apparatus of claim 16, wherein the data processing unit includes astorage unit operatively coupled to the data processor to store one ormore of the received signals associated with the monitored analytelevel, the predetermined signal characteristic, the prior signalassociated with the monitored analyte level, and the output data,associated with the analyte monitoring device.
 20. The apparatus ofclaim 16, wherein the predetermined signal characteristic includes adetermination of a predetermined number of received signals below thepredetermined level.
 21. The apparatus of claim 20, wherein thepredetermined signal characteristic includes the determination of thepredetermined number of received signals below the predetermined levelfor a first predetermined time period.
 22. The apparatus of claim 21wherein the predetermined signal characteristic further includes adetermination of a predetermined number of prior signals above thepredetermined level for a second predetermined time period.
 23. Theapparatus of claim 16, wherein the predetermined signal characteristicincludes a determination of a predetermined number of prior signalsabove the predetermined level.
 24. The apparatus of claim 16, whereinthe predetermined signal characteristic includes the determination ofthe predetermined number of prior signals above the predetermined levelfor a second predetermined time period.